Casting machine



July 23. 1940. R. HJTAYLOR 12 I CASTING MACHINE Filed Dec. 29, 1938 WSQWEQTQR I r mw atented July 23, 1940 mreo STATES.

". I 2,208,612 cAs'rIuG meme My invention relates to an improvement in machines for casting, particularly machines for casting diamond drill bits.

is the provision of a drillbit in which the matrix or drill body is free of blo'wholes. A still further object is the provision of a diamond drill bit in which the diamonds or cutting stones are more N fully embedded than in prior structures, and in which more diamonds can be successfully employed than possible heretofore.

More specificallymy invention is directed to an improvement in centrifugal casting machines w for casting diamond drill bits. Under present practice it is customary to place the diamonds or cutting stones in a mold, the mold then being revolved, while molten metal is being poured into it. Centrifugal force throws the metal outwardly 20 into contact with the moldcavity and with the diamonds, thereby producing a matrix or drill body of the desired shape with the diamonds embedded in the face of the same. I have found it difiicult in such a process to avoid blowholes' 5 in the casting, due to inability always to rid the equipment of air contained within the mold cavity and to rid the equipment of gases generated in the casting operation. The present invention overcomes these diificul- 30 ties very satisfactorily and not only am I able to eliminate blowholes but I find the'matrix or casting is much denser, that the diamonds are held more securely and that more stones can be satisfactorily accommodated than heretofore.

In the accompanying drawing 1 have illustrated an embodiment of my invention.

Fig. l is a sectional plan view of a casting apparatus suitable for the practice of my invention;

Fig. '2 is a section on the line 2-2 of Fig. 1 Fig. 3 is a section on the line 3-3 of Fig. 2; and

Fig. 4 is a sectional elevational view of a bit made by my improved method and apparatus.

Referring to the drawing in detail: 2 designates the turntable of a centrifugal casting machine. This turntable is rotated about its central axis by any suitable driving motor.

Block l is mounted centrally of the turntable 50 and is provided with filling opening 6 which extends downwardly into the block and then hori zontally as shown at 8 into communication with the bore of a horizontally extending sleeve III which extends radially of the turntable. In line as with the sleeve I is a guide tube l2.

One object of. the invention is the provision 5 of a denser drill body or; matrix. Another object apparent that an air Rutherford H. Taylor, Millburn, N. J., assignor to I J. K. Smit & Sons, Inc., New York, N. Y., a corporation of New York a l Application December 29. 1938, Serial No. 248,24

:i Claims. (01. 22-65) The guide tube I2 is for the receptionand support of a bit coupling l4. This coupling is preformed, is usually of steeland it is to it that the matrix bf the bit is to be cast. The bit coupling and guide tube extend into the 5 cavity 06 of a mold l8. The bit coupling, mold and guide -tube are securely clamped to each other.

The mold cavity I6 extends through the outer face of the mold l8 and the outer face of the mold is cut back as shown at to receive a die plate 22. This die plate is removable. Apertures 24 extend through the die plate. This plate supports the diamonds 26 of the bit during casting.

Clamped to the outer face of the die plate by a solid plate 28 is a ventilating cylinder 36. The bottom 3| of this cylinder, that is, the end adjacent the die plate is provided with a ventilating opening 32 communicating through the apertures 24 in the die plate with the mold cavity IS. The 2!) cylinder 30 is provided in one wall with a ventilating opening 34 and diametrically opposite with another ventilating opening 36, these openings being joined by air passage 36 extending transversely of the cylinder. This opening may be provided by ribs 40 integral with the end wall or bottom 3| and upstanding therefrom. It is to be noted that the opening 34 is of much greater area than opening 36 and that the passageway or channel 38 is contracted from opening 34 toward' 36, and that this channel passes directly over the ventilating opening 32. It is to be noted also that the end wall or bottom 3| extends outwardly slightly in a direction away from the die plate, as shown at 42, adjacent the opening 32.

In operation with the machine set up for easting the cylinder 36 is so disposed that the large opening 34 leads the smaller opening as the mold revolves. As the turntable 2 is rotated it will be current is continuously 0 forced through the cylinder 30, the air entering the opening 34, passing through the gradually restricted passage 38 across the mouth of the opening 32 and discharging through the wall opening 36.

It will be apparent that the construction above described provides for the ready escape of the air and generated gases from the mold cavity l6 as the molten metal is thrown outwardly by centrifugal force into the mold cavity and against the cutting stones, this air and the gases being picked up and carried out of the apparatus by the current of air rushing across the opening 32 due to rotation of the turntable.

- I have found in practice that my improved I method and apparatus produce a much denser tasting than possible heretofore by prior apparatiis, that the casting is free of blowholes and that the diamonds are more fully and firmly embedded therein. I find also that I am able to employ more diamonds to a given area than heretofore possible due apparently to the denser casting produced and the improved embedding of the stones which I obtain.

It is to be understood that changes may be made in the details of construction and arrangement of parts hereinabove described with tin the purview of my invention. For example,

the cylinder 30 could simply be a tube extending said member joining said apertures, the bottom wall of said air channel adjacent the die plate being provided with an aperture communicating with the mold cavity, the sides of said air channel converging toward each other from the leading side wall of the member to the trailing side wall, whereby as the mold is revolved a reduction in pressure will be produced on the aperture in the bottom wall of the air channel.

2. Casting apparatus comprising in combinae tion a mold, means for revolving the same, a die plate for supporting cutting stones in the mold, a member secured to the mold to the rear of the die plate and revolving with the mold and die plate, said member being provided in its leading side wall and in its trailing side wall wit-hen aperture, said apertures being diametrically opposite each other, the aperture in the leading side wall being or larger area than the aperture in the trailing wall, said member being provided internally with an air channel converging from the larger aperture to the diametrically opposed smaller aperture, the bottom of said air channel adjacent the die plate being provided with an aperture communicating with the mold cavity, whereby as the mold is revolved with the larger Wall aperture leading, a reduction in air pressure will be'produced on the aperture in the bottom wall of the air channel to eiiect a reduction in the pressure in the mold cavity.

3. Casting apparatus comprising in combina tion a mold-means for revolving the same, a die plate for supporting cutting stones in the mold, a member secured to the mold to the rear of the die plate and revolving with the mold and die plate, saidmember being provided in its leading side wall with an aperture and in its trailing side wall with a smaller aperture, an air channel with- ,in said member extending from the said larger aperture and converging to the said smaller aperture, the bottom wall of said air channel adjacent the said smaller aperture being provided with a slot communicating with the mold cavity, whereby as the mold revolves suction will be produced on the mold cavity.

- RUTHERFORD H. TAYLOR. 

